The present invention relates to a design system for building folding boats, and more particularly to a ultra lightweight collapsible, easily transportable, easy-to assemble Kayak with a structurally secure monocoque, rigid hull and deck system. Eliminating the use of the traditional rib and stringer skeletal frame with outer skin. This is achieved through an improved hull design and construction method and the unique state of the art materials used therein.
So called xe2x80x9cfolding boatsxe2x80x9d, kayaks and canoes have been known for hundreds of years but hitherto have been constructed using the conventional methods of skin over wooden frame or more recently treated canvas or nylon material stretched over an aluminum frame. This creates a very heavy, complicated, craft, which is ill-suited for lightweight back packing, simple quick assembly and small space storage.
Disadvantages of these conventional methods include increased hull drag, which reduces speed and increases expended effort by the paddler. This condition is caused by the lack of inherent support between the hull stringers. (E.G. U.S. Pat. No. 4,821,666 HULL CROSS SECTIONS) which allows the skin to flex inward under water pressure and create pockets and ridges to disrupt the smooth flow of water across the hulls bottom surface. In addition, there is excessive hull flexure inherent in the skin over frame construction that allows the hull to distort its shape as waves pass under it again causing increased drag, paddle effort and friction ware on components. This creates the need for heavier skin materials and more maintenance.
The conventional frame construction methods (E.G. U.S. Pat. No. 4,841,899 WOODEN FRAME AND HARDWARE PIECES), by their inherent design require a high number of wood, plastic, and metal components. (Over 250 in U.S. Pat. No. 4,4841,899). These components increase the complexity, cost, weight and assembly time of this method. Included in the more recent conventional frame and skin folding boats, kayaks and canoes is the use of inflatable sponsors or devices needed to strengthen the hull structure and tighten the skin. These devices also increase total weight, while adding cost in an attempt to create a more ridge hull and eliminate/replace hull flexure. (E.G. U.S. Pat. No. 4,751,889 FIG. 2 ITEMS 60 AND 61) Other drawbacks to following the traditional skin over frame concept with canoes, kayaks, dinghies, and other small boat designs are the shear bulk and weight of these vessels. This often necessitates more than one storage container or bag and the weight of these craft""s restrict their use as a true back pack-able boat to be taken along with the necessary camping gear for extended times or distances by a single person. This creates the need to leave important camping gear behind because of the weight or bulk of current folding boat conventional designs. Maintenance is another concern with the conventional skin over wooden and aluminum frames. The user must continually inspect and carefully refinish or otherwise provide a continual protective coating on the wood, aluminum and metal components to prevent delaminating of the wood, corrosion of aluminum and rust of any other metal components.
Performance issues experienced with prior art include excess flexibility in some canoes currently commercially available such as Jensen U.S. Pat. No. 4,290,157. Other folding canoes, which are similar to the Jensen design, have inherent structural weakness that creates problems for users; such as when the paddler sits in the center of the canoe with no weight in each end.
This creates excessive rocker making the hull form into a banana shape. Conversely, if two paddlers sit one in each end of the canoe the hull forms a reverse rocker, looking like an upside-down banana. Both of these conditions create maneuvering and handling problems along with excessive stress on the hull frame structure.
Collapsible, portable, or folding boats disclosed in U.S. Pat. Nos. 3,869,743; 8,338,46; 2,053,755; AND 598,989 represent prior art using extremely complicated hull frames that are complicated and time consuming to assemble. They have a plethora of small loose parts, rib connectors, and ancillary other components that are easy to loose and difficult to use, adding time and frustration to the assembly procedure. The added weight of this prior art make many folding boats unsuitable for pack packing as disclosed in U.S. Pat. Nos. 381,137; 1,920,130; 4,290,157 FIG. 9: U.S. Pat. No. 4,751,889; FIG. 3 thru U.S. Pat. No. 6; 1,920,130; 3,004,370; 4,110,951 and 3,932,049 represent a wide variety of fasteners used for securing tubular components within an assembly. There is a common thread woven through all of these connectors and that is their high cost, complexity and some are not well suited for their use in collapsible portable watercraft frames and are known to fail during use. They also represent higher component and installation costs to the folding boat manufacture and this cost is passed on to the end user. Folding dinghy""s disclosed in U.S. Pat. Nos. 4,124,910; 4,697,540; 4,250,583 fold but do not totally disassemble into a small package suitable for transportation in a car trunk or boat cockpit locker and their weight limits their use for back packing.
Collapsible boat U.S. Pat No. 2,994,891 represents the skin and frame prior art and therefore enjoys the same limitations of weight, size, complexity, high manufacturing costs, small space storage, transportation and back packing capability.
Foldable boat U.S. Pat. No. 5,975,005 this prior art uses rigid hull forming sections with a separately attached hinging system to facilitate folding of the hull forming sections. A special molded, interlocking engagement projection configuration is used to join the hull forming sections together in an effort to add lateral strength to the assembly and capture the ends of the hull forming sections into a unit. The materials listed (I.E. Aluminum titanium, rigid wood, fiber-reinforced plastic, epoxy, polyester, polyethylene, resins reinforced with glass fiber, carbon fiber or the like) are all materials requiring special machining, molding processes and tooling, which are all specialized, expensive materials and manufacturing processes. The flexible members, and tightening piece and hooks used to assemble the foldable boat and hold it together present some risk to the boat operator if one of the top, side flexible members loosen or lets go. This would potentially allow the water pressure to push in the side allowing water to enter the boat in large quantities over the topside of the hull forming side member. Other limitations of this prior art are the box shape and potential for use of more streamlined hull shapes used in dinghies, kayaks and canoes. High flotation loss due to the volume and weight of the hull forming members and assembly flexible members and hardware, will reduce the total load carrying capacity.
In summary, this prior art employs a design and materials that limit its application to basically box type boat shapes that are heavy, have little aesthetic appeal and would not be suitable for use in canoe, kayak, dinghy, or other folding watercraft, used in backpacking or light weight folding water craft, used in backpacking or light weight folding boats construction and manufacturing.
It is the object of this present invention to overcome the disadvantages of the prior art and provide a collapsible kayak, canoe or folding boat that is super light weight with a rigid hull having a minimum of components that will provide performance more typical of non-folding rigid hull watercraft.
It is also the specific goal of this present invention to provide here-to-fore unattainable hull rigidity with the inherent lightweight and simplicity of construction and assembly needed in higher performance lower cost portable watercraft. It is also the specific goal of this present invention to eliminate the use of the traditional skeletal frame with all its separate support members, clamps and special complex fasteners through the novel use of extruded corrugated high density plastic sheet coupled with a unique simple method of constructing semi-rigid hull and deck sections for folding, portable, light weight watercraft.
It is also a specific object of this invention in connection with the construction of a folding boat, canoe, dinghy or kayak, to provide by incorporation of extruded corrugated plastic, enhanced resistance to hull and skin flexure with improved through the water performance more like a rigid hull shell than a folding boat.
It is also a specific object of this invention to reduce flotation loss and increase load carrying capacity through the unique use of light weight extruded corrugated, high-density plastic sheet and elimination of the skeletal frame and its components reducing the total weight of the watercraft thus increasing the load carrying capacity of the watercraft.
It is further the specific object of this invention to eliminate the unsupported hull skin areas allowing for a lighter waterproof skin with fewer reinforcements, lighter weight and elimination of the need for air-bladder skin tightening and hull strengthing systems.